The present invention relates to the use of deformable polyurethane wheels in polishing, finishing and deburring operations and, more particularly, to an elastomeric polyurethane polishing and finishing wheel of high tensile strength which functions in an improved manner and has an exceptionally long useful life.
At the present time, setup wheels are widely used to carry out polishing and finishing operations on metal parts despite a number of recognized drawbacks. Such wheels are built up of a plurality of pieces of cloth which are coated with abrasive material. The useful life between setups (renewal of the abrasive coating) tends to be relatively short and costs are high, but the setup wheels are used nevertheless because of lack of superior substitutes.
To some extent the setup wheels have been replaced by flexible spirally-wound abrasive wheels formed by wrapping abrasive coated woven nylon material or the like, such as the "Tycro" finishing and deburring wheels made by Minnesota Mining and Manufacturing Company, but such spirally-wound abrasive wheels wear out very rapidly and so fast that they are impractical for use in various machines because of the time required for wheel replacement.
Abrasive belts and other abrading equipment have also been used for polishing and finishing operations but they are generally less popular than the setup wheels and spirally-wound wheels mentioned above.
Rigid polyurethane grinding wheels have been disclosed, for example, in U.S. Pat. No. 3,377,411, and various wire brushes have been made with a reinforcement of polyurethane or other thermosetting synthetic resin material, as disclosed, for example, in U.S. Pat. Nos. 3,129,269; 3,147,503 and 3,142,081. An abrasive wheel is disclosed in U.S. Pat. No. 3,252,775 made of a soft low-density polyurethane foam, but this type of wheel has poor strength and poor wearing properties and has not been successful commercially. During the last decade the industry has employed different types of wheels for polishing operations such as cork wheels or spirally-wound wheels. It was not recognized, prior to the present invention, that polishing and surface refining operations could be carried out more effectively using abrasive wheels made of a flexible solid polyurethane elastomer.